1. Field of the Invention:
This invention relates to interconnection circuitry and, more particularly, to methods and apparatus for handling data within a computer system in a manner that a plurality of data sources can transfer information to a plurality of destinations concurrently.
2. History of the Prior Art:
The typical computer system utilizes a busing arrangement as its primary interconnection to transfer information from one component of the system to another. In such a system, a component such as a central processor directs information to another component by placing the address to which the information is directed on the system address bus and the information on the system data bus. The destination for the information recognizes an address within its range of addresses and accepts the information available on the data bus. Each of these buses is made up of a number of conductors (for example, thirty-two) which physically connect to each of the system components. During the time that any particular source of information is utilizing the buses, they are unavailable for use by any other source since all of the conductors of each bus available to carry either address or data information are occupied. Consequently, information may be sent by only one source at a time (although more than one destination may receive information if more than one destination can respond to the same address) since there is no room for information from more than one source at a time on the data or address buses.
Typically, a bus arrangement has sufficed for transferring information in the typical personal computer or work station. However, the requirements for pathways to handle more and more information faster have increased to the point that various functions cannot be performed by the typical busing arrangement. Functions such as the presentation of animated graphics and television require the transfer of so much information that they tend to require that the entire system be devoted to their use. When it is desired to incorporate a number of these functions into the same computer system and to run more than one of these operations at the same time, a busing arrangement is incapable of handling the load.